Does anyone have a feel for how much delay between key and sidetone is tolerable or comfortable for a competent CW operator? Thank you in advance.

I commonly use a keyer at up and beyond 30WPM, where each dit is about 25ms. It would feel odd to me at least, if a sidetone was more than a dit (25ms) behind. I'm sure I would never ever be able to detect just a few ms.

Note that in many QSK-type transceivers, actual keying is as much as 10 to 30ms behind key closure. See e.g. ARRL rig reviews for keying waveforms. When I switch between different rigs at different sites and the delay changes I can kinda feel "the timing is funny" between key closure and actual TX but I can adapt to delays like this.

Then I can go back to my "true QSK" setup (separate TX and RX, so no IF flopping between modes on each keychange) and I feel "oh this is great, nothing feels weird about this at all, this is the way it's supposed to be."

So I would say a delay of 10-30ms is noticeable but humans can adapt to it.

Does anyone have a feel for how much delay between key and sidetone is tolerable or comfortable for a competent CW operator? Thank you in advance.

It would be "zero," for me. I sometimes send at about 50 wpm and even a few mS delay would be kind of a disaster.

Now, that's the delay between key closure and sidetone, not necessarily the RF envelope. I can't hear that, so if there's latency between key closure and RF output it wouldn't matter (and there always is, since I have my QSK keying loop set for about 15mS or so -- meaning the amplifier keys first, the RF follows that).

Many thanks for all the replies. Yes, it's an SDR rig I'm working on so the audio has to pass through the sound system of the operating system. Seems to be difficult to use very short buffers without running into underrun problems.

Does anyone have a feel for how much delay between key and sidetone is tolerable or comfortable for a competent CW operator? Thank you in advance.

Zero for me also. I can't imagine why there would be any sidetone delay in a rig.

When operating QSK and with sidetone generated on the rig... you gotta hear either the receiver or the sidetone. Can't hear the sidetone at the same time the rig is in receive.

With most "modern" QSK transceivers (IF shared between TX and RX), the delay between key closure and and actual transmit envelope is circa 10-20ms. This is something I can adapt to and work with and I would guess others can too. Read the ARRL reviews of modern QSK transceivers to see typical RF out vs key closure:

Of course there are other, more traditional ways to achieve "true QSK" without any such delay. And when I switch from a modern transceiver rig to older separate RX and TX, it feels "more right" to not have the 10-20ms delay.

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